Systems for combined CT imaging and therapeutic irradiation of patients are disclosed, for example, in patent application US 2003/0048868 A1. This patent application discloses a combined therapeutic irradiation and imaging system that on the one hand has a CT scanner with at least one x-ray tube and a detector situated opposite, the x-ray tube and the detector being fastened on a rotary frame (=gantry) and revolving in a fashion rotating thereabout for the purpose of scanning a patient while the patient is being pushed through the scanning area along the system axis by a displaceable patient couch. In addition, a separate irradiation apparatus, which serves for irradiating the patient therapeutically, is provided outside the gantry, but in the scanning plane of the gantry. The patient can thereby be scanned by the CT scanner without changing position, and subsequently be exposed directly to therapeutic irradiation without needing to be moved.
A device comparable thereto is known from the “TomoTherapy” company; it includes a conventional CT unit that is supplemented by an additional linear accelerator for therapeutic irradiation such that there is no need here either to reposition the patient between the scanning process and the irradiation.
Such devices are very expensive to manufacture and require a large amount of space owing to the combination of two basic units, and for this reason their market penetration has so far been slight.